<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .parent{
            width:200px;
            height:200px;
            background: red;
        }
        .child{
            width:100px;
            height:100px;
            background: yellow;
            margin: 50px;
        }

    </style>
</head>
<body>
    <div class="parent" id="parent">
        <div class="child" id="child">

        </div>
    </div>
    <script>
        // 事件冒泡就是父元素和子元素绑定了相同的事件，子元素的事件执行的时候，父元素的事件也会触发。
        // 阻止事件冒泡，event.stopPropagation();
        var parent=document.getElementById("parent");
        var child=document.getElementById("child");
        parent.onclick=function(event){
            alert("parent");
            event.stopPropagation();
        }
        child.onclick=function(event){
            alert("child");
            event.stopPropagation();
        }
    </script>
</body>
</html>